# RisingWave

[RisingWave](https://risingwave.com) is a distributed streaming database that enables
processing and management of real-time data with a Postgres-style SQL syntax. It is
available as an [open-source edition](https://github.com/risingwavelabs/risingwave)
and a managed cloud service.

## Prerequisites

- [Credentials](https://docs.risingwave.com/docs/current/risingwave-docker-compose/#connect-to-risingwave) for the RisingWave cluster

## Setup

RisingWave provides a Postgres-compatible interface. You can connect Cube to RisingWave
as if it's a regular [Postgres][ref-postgres] data source.

### Manual

Add the following to a `.env` file in your Cube project:

```dotenv
CUBEJS_DB_TYPE=postgres
CUBEJS_DB_HOST=risingwave_host
CUBEJS_DB_PORT=risingwave_port
CUBEJS_DB_NAME=risingwave_database
CUBEJS_DB_USER=risingwave_user
CUBEJS_DB_PASS=risingwave_password
```

## Environment variables

| Environment Variable | Description                                                                         | Possible Values           | Required |
| -------------------- | ----------------------------------------------------------------------------------- | ------------------------- | :------: |
| `CUBEJS_DB_HOST`     | The host URL for a database                                                         | A valid database host URL |    ✅    |
| `CUBEJS_DB_PORT`     | The port for the database connection                                                | A valid port number       |    ❌    |
| `CUBEJS_DB_NAME`     | The name of the database to connect to                                              | A valid database name     |    ✅    |
| `CUBEJS_DB_USER`     | The username used to connect to the database                                        | A valid database username |    ✅    |
| `CUBEJS_DB_PASS`     | The password used to connect to the database                                        | A valid database password |    ✅    |
| `CUBEJS_DB_SSL`      | If `true`, enables [SSL encryption](https://docs.risingwave.com/docs/current/secure-connections-with-ssl-tls/) for database connections from Cube | `true`, `false`           |    ❌    |
| `CUBEJS_CONCURRENCY` | The number of concurrent connections each queue has to the database. Default is `2` | A valid number            |    ❌    |
| `CUBEJS_DB_MAX_POOL` | The maximum number of concurrent database connections to pool. Default is `8`       | A valid number            |    ❌    |

## Pre-aggregation feature support

### `count_distinct_approx`

Measures of type
[`count_distinct_approx`][ref-schema-ref-types-formats-countdistinctapprox] can
not be used in pre-aggregations when using RisingWave as a source database.

## Pre-aggregation build strategies

<InfoBox>

To learn more about pre-aggregation build strategies, [head
here][ref-caching-using-preaggs-build-strats].

</InfoBox>

| Feature       | Works with read-only mode? | Is default? |
| ------------- | :------------------------: | :---------: |
| Simple        |             ✅             |     ✅      |
| Batching      |             -              |      -      |
| Export bucket |             -              |      -      |

By default, RisingWave uses a simple strategy to build pre-aggregations.

### Simple

No extra configuration is required to configure simple pre-aggregation builds
for RisingWave.

### Batching

RisingWave does not support batching.

### Export bucket

RisingWave does not support export buckets.


[ref-postgres]: /product/configuration/data-sources/postgres
[ref-caching-using-preaggs-build-strats]: /product/caching/using-pre-aggregations#pre-aggregation-build-strategies
[ref-schema-ref-types-formats-countdistinctapprox]: /reference/data-model/types-and-formats#count_distinct_approx